How Much Protein Do You Really Need? What the Research Says

The recommended daily allowance (RDA) for protein is 0.8g per kilogram of body weight. And if your goal is simply to not develop a protein deficiency, that's fine. But if you're trying to build muscle, lose fat, or do both at the same time — the RDA is not your number.

Here's what the peer-reviewed research actually recommends, broken down by goal.

The RDA is a minimum, not an optimum

The RDA of 0.8g/kg was established to prevent deficiency in sedentary individuals. It was never designed for people who resistance train, run calorie deficits, or care about body composition. Using the RDA as a protein target when you're training is like using the minimum wage as your salary target — technically sufficient, practically inadequate.

Protein for fat loss: 1.8–2.7g per kg

When you're in a calorie deficit, your body doesn't just burn fat. It also breaks down muscle tissue for energy. Higher protein intakes during a deficit protect lean mass — this is one of the most well-supported findings in sports nutrition research.

Helms et al. conducted a systematic review in 2014 specifically examining protein needs during caloric restriction in resistance-trained athletes. Their conclusion: 1.8–2.7g of protein per kilogram of body weight per day during a cut.

The higher end matters most when you're already lean (under 15% body fat for males, under 25% for females) or when your deficit exceeds 25%. If you're at a moderate deficit and have more body fat to lose, the lower end is fine.

Reference: Helms, E.R. et al. (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes. IJSNEM, 24(2), 127-138.

Protein for muscle building: 1.6–2.2g per kg

The landmark meta-analysis by Morton et al. (2018) pooled data from 49 studies with 1,863 participants. Their finding: protein intakes up to 1.6g/kg/day significantly augmented resistance training-induced gains in muscle mass. Beyond 1.6g/kg, the additional benefit flattened — but there was no downside to going higher.

Practical recommendation: aim for 1.6–2.2g/kg during a muscle-building phase. The upper end is unnecessary but not harmful, and it provides a margin of safety for days when protein distribution isn't perfect.

Reference: Morton, R.W. et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. British Journal of Sports Medicine, 52(6), 376-384.

Protein for maintenance: 1.4–2.0g per kg

If you're eating at maintenance and training regularly, you're not fighting the muscle-sparing battle of a deficit or trying to maximise growth. A moderate protein intake of 1.4–2.0g/kg is sufficient to maintain lean mass and support recovery.

Does protein timing matter?

Less than you think. The "anabolic window" — the idea that you need protein within 30 minutes of training — has been significantly overstated. Schoenfeld et al. (2013) found that total daily protein intake matters far more than timing.

That said, distributing protein across 3–5 meals per day (rather than cramming it all into one sitting) does appear to optimise muscle protein synthesis. Aim for 20–40g per meal as a practical guide.

Reference: Schoenfeld, B.J. et al. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. JISSN, 10, 53.

Do you need protein supplements?

Protein powder is food, not a supplement. It's dried milk protein (whey) or plant protein in a convenient form. If you can hit your protein target through whole foods, you don't need it. If you can't — because of time, convenience, or appetite — it's a practical tool to close the gap.

There is nothing magical about whey protein. It doesn't build more muscle than chicken, eggs, or Greek yoghurt at the same dose. It's just faster to prepare.

The bottom line